Hi Patricio,
This is definitely a tough one to answer, as disk usage by enterprise database servers can vary heavily depending on the configuration. Assuming a pretty standard configuration, in a base installation with little to no additional operations performed on the database, the size is going to be around roughly 450-500M in terms of the amount of space the nolio tablespace uses on disk, eg(5.x installation):
-rw-r----- 1 oracle oinstall 501M Mar 16 12:10 nolio_tbs.dbf
To answer your question about where the tablespace is typically located on disk, you will find them usually stored in(of course substitute the base path to your oracle install):
/u01/app/oracle/product/11.2.0/db_1/dbs
The file extension by default with 11g is .dbf, the only other tablespace nolio utilizes by default is a temporary tablespace which is of negligible size.
Let me know if this helps and if you have any additional questions, thanks!
Jeremy